Human white blood cells express proteins called APOBEC-1 related proteins (ARPs), which are cytidine deaminases that can change the genetic code of an infecting virus. These changes can render the virus incapable of producing an infection when they occur in critical genes encoding viral proteins and/or when they occur extensively throughout the viral genome. APOBEC-1 related proteins (ARPs), such as CEM-15, APOBEC-3B, APOBEC-3C, and APOBEC-3F have been found to have a deleterious effect on HIV-1, HIV-2, retrovirus and hepatitis B. HIV-1, however, expresses a protein called Viral infectivity factor (Vif) that impairs the ability of ARPs such as CEM15 to act on viral DNA.
A small subset of HIV-infected individuals, known as long-term nonprogressors (LNTPs) have substantially slower rates of disease progression in the absence of therapeutic intervention. Clinically, these LTNPs are usually asymptomatic, maintain high CD4 counts and low HIV viremia levels. The characteristics are therefore of prognostic value in evaluating disease severity. The mechanisms responsible for long-term nonprogression have been attributed to defective or less fit HIV variants, strong host immune responses and unique host genetic elements, such as the CCR5 genotype and HLA haplotypes (Buchbinder et al. (1999) Microbes and Infection 1: 1113-1120).
Thus, needed in the art are methods and compositions related to determining the status and mechanisms underlying long-term nonprogression of viral infections. More specifically, the role of APOBEC-1 related proteins in viral progression and its affect in long-term nonprogressors is of importance.